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easy to add extra 1,2,4 UART for Raspberry Pi Zero B+ 2B 3B
easy to add extra 1,2,4 UART for Raspberry Pi Zero B+ 2B 3B
28 backers pledged £1,217 to help bring this project to life.

About this project

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Update 04 Oct 2016

1xUART and 2xUART will be updated to include a HAT EEPROM at no extra charge. Please see the Update #1 for more information.
Thank you for all of your support.
Project Background   

 During development / research for a project which needs more than 1 UART Port, the common replacement for the Raspberry Pi is the "Arduino MEGA". This is because the MEGA provides 4 UART's which can be used at the same time creating a multi UART device.

When using UART on the Raspberry Pi you are very limited on how you work around this limitation, but we also know that the Pi 3B has a built in WiFi & Bluetooth module. In the Raspberry Pi 3B the Bluetooth uses the only UART which further limits the use of the Pi. Most solutions for external UART controllers come as a USB to UART converter, which takes up space and brings the design out of the Raspberry Pi's small form factor.

To counteract all the limitations of the Raspberry Pi, we have built a board which simply connects through the Pins on the Raspberry Pi as usual, but include access to extra UART's without limiting the Pi any further or without a special image.

The current board range will fit on all the Raspberry Pi's to Date ( September 2016 ), The Lite versions of the boards will fit on the Pi Zero without a problem or modification. The Boards rise less than 1cm above the original form factor. 

Included is our own software which manages, controls, and watches the UART ports. The software comes as a terminal program, and GUI programs, each will report the port location for easy to use for easy integration into any project.

We use Raspbian Jessie; Version: May 2016, Release date: 27th May 2016, Kernel version: 4.4 Because we have created our own driver which manages the setup and the control of the serial ports which allows the user to apply changes on the fly, We haven't gone down the route of a kernel but instead chosen to write a Driver for the serial ports. This manages everything from setting up the ports, monitoring changes such as closing the port and reopening it etc.

Glossary:

UART - Universal asynchronous receiver/transmitter: A protocol to communicate with another device in which they devices send and receive commands, words, numbers which the other device interprets.

RS232 - A Standard for transmitting from one serial device to another device through a specified speed ( BPS or Bits per Second ). 1's are represented by a Negative voltage such as -3.3V and a 0 being 3.3V.

Pi UART - The standard serial port on the Raspberry Pi on Physical Pins TX/RX 8 & 10 or BCM 14 & 15.

TTL - Similar to RS232 but instead of a logic high ( 1 ) being a negative voltage e.g. -3.3V, TTL is 0 to VCC ( 3.3V ).

Terminal - A text based user interface such as Command Prompt for the Windows Operating system, or LXTerminal for Raspbian Jessie.

GUI - A graphical user interface, this is usually the easiest way to represent data and is interactive. A good example of a GUI is a windows program such as the file browser, it is a User Interface using graphics and text. A terminal or text based version would be something such as the command "ls" in linux where there are no graphics and it can be shown in a terminal.

Driver - Software that is used to control hardware from a Computer such as a Laptop or a Raspberry Pi. An example would be drivers for a webcam on a computer, the drivers would interpret the messages being sent from the webcam and convert them to images / video.

Port - Sometimes a physical location on hardware e.g. USB Port, but can sometimes also be a non-physical location such as "/dev/pts/X" on Linux for the serial connections.

HAT - Plug and Play add on board for the Raspberry Pi which allows the Pi to load the correct software / drivers for each board.

Jumper Connection - A physical connection on the board which can be connected via a small electrical component ( usually a small "clip" which connects two pins on a board ). A picture is below:

Jumper Connection
Jumper Connection

 The connection above will select RS232 ( Left side is RS232 and Right side is TTL Selector ). You can select one for each channel such as RS232 for UART 1 and TTL for UART 2.

What Is It? 

 UART HAT is Add-on board for Raspberry Pi which provides 1, 2, and 4 additional RS232/TTL serial ports with flow control which are 3.3 V compatible in addition to the original Serial Port of Raspberry PI.

What is the use of the HAT?

As we know Raspberry Pi has only one Serial Port with only 1 RX and TX pins which is primarily used for Debugging / Wired Console use. If we need to connect any serial devices to raspberry pi we have to disable the console and then we need to connect. And all with this pain we can connect only one serial device to Raspberry Pi at a time. To overcome the all these problems we have developed the UART HAT which helps to Connect multiple serial devices such as GPS, GSM, Bluetooth 2.0/4.0 module, Arduino Pro Mini, Thermal Printers, and anything else that requires a serial port connection.

Why not use a USB to UART?

During usual operation the keyboard and mouse will be used constantly, as well as a WiFi USB Adapter, and/or a USB Flash storage device for transferring projects back and forth. With this it leaves you with no spare USB slots or 1 USB slot at best. This limits you to just another USB to UART port, which makes you use /dev/ttyUSBx where x can be any number. In our software we assign an ID number also called our PiCom number. in a 4 port UART it goes from 1 to 4. You can then check /dev/picom1 /picom2 etc. and you will receive the pts number for easy development / usage. Or using our GUI its just one click away from starting up and being able to instantly communicate.

Along with these positives, you can load up to 4 different UART's at the same time. Our Aim We at Pridopia want to receive more feedback on how we can improve / update our software & hardware to meet the requirements of our customer base and improve the way you use the UART-Pi. What you get: The board is already sold assembled and ready to use.

The UART-Pi System will work with all the Raspberry Pi A+, B+, 2B, 3B, Pi Zero models. Contact / Support / Ideas / Feedback - Twitter: https://twitter.com/pridopia ,Email: kickstarter@pridopia.co.uk

Delivery:

Delivery In the UK: First Class recorded with tracking number.

Outside UK: Royal Mail International sign for with tracking number. If you want to order more than one product, Calculate the cost and add it to your pledge and then please email or message us. If your pledge is more than the average amount we will try to contact you once the Kickstarter period is over to confirm which boards you want to receive.

Different Boards:

General features:

  • Single / Dual full-duplex UART
  • Baud rates up to 921600 ( Raspbian will support up to 460800 )
  • Auto Hardware Flow Control using RTS/CTS
  • 64byte FIFO Buffer ( TX & RX )
  • 5/6/7 or 8bit characters
  • Even/Odd or No Parity
  • 1/2, 1, or 2 Stop bits
  • Works on all Raspberry Pi's ( 4xUART won't fit on a Pi Zero )

1. 1xUART Lite (1uart-Pi-Ze-Li)

extra 1 UART HAT
extra 1 UART HAT

 

1. provide extra 1 UART  TTL/232

  •  UART HAT RS232 output TX,RX 
  •  UART HAT TTL output TX,RX,GND,3V3,CTS,RTS  

2. Pi UART can select TTL/232 output 

  •  Pi UART TTL output TX,RX,GND,3V3,XX,XX
  •  Pi UART RS232 output GND, TX, RX

3. i2c signal out GND,5V,SDA,SCL for extend extra UART HAT

2. 2xUART Lite (2uart-Pi-Ze-Li)

extra 2 UART HAT
extra 2 UART HAT

 1. provide extra 2 UART TTL output

  •  TTL output signal  --> TX,RX,GND,3V3,CTS,RTS

2. Pi UART can select TTL/232 output 

  • Pi UART RS232 output GND, TX, RX
  • Pi UART TTL output TX,RX,GND,3V3,XX,XX 

3. i2c signal out GND,5V,SDA,SCL for extend extra UART HAT

3. 4xUART (4uart-TTL)

extra 4 UART HAT
extra 4 UART HAT

 

1. provide extra 4 UART TTL output 

  •  4x UART TTL output TX,RX,GND,3V3,CTS,RTS 

2. Pi UART can select TTL/232 output 

  •  Pi UART RS232 output GND, TX, RX
  •  Pi UART TTL output TX,RX,GND,3V3,XX,XX 

3. 2 set i2c signal out GND,5V,SDA,SCL for extend extra UART HAT 

4. TTL UART1 support ESP8266 WiFi module socket

Projects

Project 1:

This project is about controlling a Arduino or other micro-controller with a Raspberry Pi. We achieve this by sending commands over a Bluetooth module to the Micro-controller which has a Bluetooth module as well. The list of items needed for this project is:

  • 1 x Arduino / Micro-controller with Serial communication
  • 1 x Raspberry Pi
  • 1 x 1 UART Board ( can also use 2, or 4 UART Boards )
  • 2 x HC-05 ( Bluetooth Serial Modules )
  • 8 x LED's
  • 1 x 330Ω Resistor
  • 1 x 3.3V Power Supply ( for Arduino )
  • Lots of Male to Female, Male to Male, Female to Female wires

Outcome:

Raspberry Pi Side ( Transmitter / Controller )
Raspberry Pi Side ( Transmitter / Controller )

 

Arduino Slave - Receives Bluetooth Commands
Arduino Slave - Receives Bluetooth Commands

 

Once the Arduino is wired up, You need to upload the code to the Arduino using the IDE. The code for both Arduino and Raspberry Pi will be supplied within the ZIP / RAR file upon Kickstarter finish. 

Once all is setup, you can use the Raspberry Pi to send commands such as Flash, On, Off, KITT ( reproduces the effect from the KITT Car's light bar ). This is just the beginning, attach a GPS system and you have a GPS Locator which can be tracked from a bluetooth device.

The output on the Arduino Side should look like this:

Arduino Example Using 4xLED
Arduino Example Using 4xLED

 

Raspberry Pi Side, Bluetooth module is in UART 2
Raspberry Pi Side, Bluetooth module is in UART 2

 Reward:

Reward
Reward

 

 

Risks and challenges

We started the Kickstarter project in order to reduce the overall cost of manufacturing the boards ( More boards ordered = Lower assembly fee & lower cost for chips ). We currently design & manufacture boards already but this project would be on a much larger scale with more boards ordered and assembled.

The software is already finished but will go through several more phases and updates. As we have been producing excellent quality boards for around 10 years we do not see this as a risk.
To see our previous projects and products go to http://www.pridopia.co.uk/ixx-rspi.html for Raspberry Pi Specific boards.
We already have a small batch of boards running fine and going through the paces with no problems to report.

We are very confident that we will succeed in the 30 -60 Day time-frame and be shipping out products Nov - Dec 2016 ( depending on order size, shipping locations, and factory assembly )

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  1. Select this reward

    Pledge £13 or more About $17

    1xUART Lite

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    4xUART

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Funding period

- (20 days)